1. Field of the Invention
This invention relates to an improvement in a fluid jet loom in which a weft yarn is picked under the influence of fluid jet, and more particularly to a method for detaining the weft yarn prior to weft picking and a weft detaining device for accomplishing the method.
2. Description of the Prior Art
A variety of weft storage methods and devices have hitherto proposed to accomplish effective weft detaining prior to weft picking. One of these is disclosed, for example, in Japanese Patent Publication No. 55-49177 and arranged to detain a weft yarn between a weft package and a weft inserting device. This weft storage device consists of a plurality of rollers arranged in the shape of a reel or swift to form a roller reel on which the weft yarn is wound in the shape of a coil. The axis of at least a part of rollers is not contained in any of planes containing the axis of the roller reel and is parallel with one of the planes. Accordingly, the weft yarn is fed to the winding end section of the roller reel so as to form a continuous coil of the weft yarn there, and the thus formed weft yarn coil is advanced to the unwinding end section of the roller reel by virtue of the rotation and the inclination of the rollers. Thereafter, the coiled weft yarn is wound off from the unwinding end section of the roller reel and drawn in the shape of balloon upon undergoing a rotation resistance, for example, by means of a brush like member installed at the unwinding end section.
With this conventional configuration, the coiled weft yarn wound on the roller reel can be advanced at a constant speed toward the unwinding end section of the roller reel by virtue of the inclination and the rotation of each roller of the roller reel, and therefore the successively coiled weft yarn is prevented from running on the previously coiled weft yarn while avoiding contact with each other. This prevents entanglement and damage of the weft yarn, and an increase in unwinding resistance of the weft yarn due to running-on of the weft yarn, thereby enabling an orderly weft storage prior to the weft picking.
However, the following drawback has encountered in such a conventional configuration. That is to say, the weft yarn is detained or wound on the roller reel upon undergoing a rotational resistance at the unwinding end section of the roller reel, and drawn in the balloon shape upon undergoing a rotational resistance even during weft picking. Thus, the weft yarn always undergoes a rotational resistance in an amount by which an excessive length of the weft yarn cannot be drawn under inertia at a termination period of the weft picking. This rotational resistance will cause mispick in case of a fluid jet loom particularly in case of an air jet loom in which weft picking force is relatively weak.